| Message ID | 20250109141440.2692173-1-jolsa@kernel.org (mailing list archive) |
|---|---|
| State | Queued |
| Commit | b583ef82b671c9a752fbe3e95bd4c1c51eab764d |
| Headers | show |
| Series | uprobes: Fix race in uprobe_free_utask | expand |
On 01/09, Jiri Olsa wrote: > > --- a/kernel/events/uprobes.c > +++ b/kernel/events/uprobes.c > @@ -1915,6 +1915,7 @@ void uprobe_free_utask(struct task_struct *t) > if (!utask) > return; > > + t->utask = NULL; > WARN_ON_ONCE(utask->active_uprobe || utask->xol_vaddr); > > timer_delete_sync(&utask->ri_timer); > @@ -1924,7 +1925,6 @@ void uprobe_free_utask(struct task_struct *t) > ri = free_ret_instance(ri, true /* cleanup_hprobe */); > > kfree(utask); > - t->utask = NULL; Acked-by: Oleg Nesterov <oleg@redhat.com>
On 1/9/25 3:14 PM, Jiri Olsa wrote: > Max Makarov reported kernel panic [1] in perf user callchain code. > > The reason for that is the race between uprobe_free_utask and bpf > profiler code doing the perf user stack unwind and is triggered > within uprobe_free_utask function: > - after current->utask is freed and > - before current->utask is set to NULL > > general protection fault, probably for non-canonical address 0x9e759c37ee555c76: 0000 [#1] SMP PTI > RIP: 0010:is_uprobe_at_func_entry+0x28/0x80 > ... > ? die_addr+0x36/0x90 > ? exc_general_protection+0x217/0x420 > ? asm_exc_general_protection+0x26/0x30 > ? is_uprobe_at_func_entry+0x28/0x80 > perf_callchain_user+0x20a/0x360 > get_perf_callchain+0x147/0x1d0 > bpf_get_stackid+0x60/0x90 > bpf_prog_9aac297fb833e2f5_do_perf_event+0x434/0x53b > ? __smp_call_single_queue+0xad/0x120 > bpf_overflow_handler+0x75/0x110 > ... > asm_sysvec_apic_timer_interrupt+0x1a/0x20 > RIP: 0010:__kmem_cache_free+0x1cb/0x350 > ... > ? uprobe_free_utask+0x62/0x80 > ? acct_collect+0x4c/0x220 > uprobe_free_utask+0x62/0x80 > mm_release+0x12/0xb0 > do_exit+0x26b/0xaa0 > __x64_sys_exit+0x1b/0x20 > do_syscall_64+0x5a/0x80 > > It can be easily reproduced by running following commands in > separate terminals: > > # while :; do bpftrace -e 'uprobe:/bin/ls:_start { printf("hit\n"); }' -c ls; done > # bpftrace -e 'profile:hz:100000 { @[ustack()] = count(); }' > > Fixing this by making sure current->utask pointer is set to NULL > before we start to release the utask object. Lets add Fixes tag for stable team: Fixes: cfa7f3d2c526 ("perf,x86: avoid missing caller address in stack traces captured in uprobe") > [1] https://github.com/grafana/pyroscope/issues/3673 > Reported-by: Max Makarov <maxpain@linux.com> > Signed-off-by: Jiri Olsa <jolsa@kernel.org> fwiw, the other version we were potentially thinking of was below, but just moving the t->utask NULL assignment seemed better. Thanks, Daniel diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index c75c482d4c52..05f9cedf2691 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -2835,6 +2835,8 @@ static bool is_uprobe_at_func_entry(struct pt_regs *regs) if (!current->utask) return false; + if (!current->utask->active_uprobe) + return false; auprobe = current->utask->auprobe; if (!auprobe)
On Thu, Jan 09, 2025 at 03:41:26PM +0100, Daniel Borkmann wrote: > On 1/9/25 3:14 PM, Jiri Olsa wrote: > > Max Makarov reported kernel panic [1] in perf user callchain code. > > > > The reason for that is the race between uprobe_free_utask and bpf > > profiler code doing the perf user stack unwind and is triggered > > within uprobe_free_utask function: > > - after current->utask is freed and > > - before current->utask is set to NULL > > > > general protection fault, probably for non-canonical address 0x9e759c37ee555c76: 0000 [#1] SMP PTI > > RIP: 0010:is_uprobe_at_func_entry+0x28/0x80 > > ... > > ? die_addr+0x36/0x90 > > ? exc_general_protection+0x217/0x420 > > ? asm_exc_general_protection+0x26/0x30 > > ? is_uprobe_at_func_entry+0x28/0x80 > > perf_callchain_user+0x20a/0x360 > > get_perf_callchain+0x147/0x1d0 > > bpf_get_stackid+0x60/0x90 > > bpf_prog_9aac297fb833e2f5_do_perf_event+0x434/0x53b > > ? __smp_call_single_queue+0xad/0x120 > > bpf_overflow_handler+0x75/0x110 > > ... > > asm_sysvec_apic_timer_interrupt+0x1a/0x20 > > RIP: 0010:__kmem_cache_free+0x1cb/0x350 > > ... > > ? uprobe_free_utask+0x62/0x80 > > ? acct_collect+0x4c/0x220 > > uprobe_free_utask+0x62/0x80 > > mm_release+0x12/0xb0 > > do_exit+0x26b/0xaa0 > > __x64_sys_exit+0x1b/0x20 > > do_syscall_64+0x5a/0x80 > > > > It can be easily reproduced by running following commands in > > separate terminals: > > > > # while :; do bpftrace -e 'uprobe:/bin/ls:_start { printf("hit\n"); }' -c ls; done > > # bpftrace -e 'profile:hz:100000 { @[ustack()] = count(); }' > > > > Fixing this by making sure current->utask pointer is set to NULL > > before we start to release the utask object. > > Lets add Fixes tag for stable team: > > Fixes: cfa7f3d2c526 ("perf,x86: avoid missing caller address in stack traces captured in uprobe") ugh right, thanks for finding that jirka > > > [1] https://github.com/grafana/pyroscope/issues/3673 > > Reported-by: Max Makarov <maxpain@linux.com> > > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > > fwiw, the other version we were potentially thinking of was below, but > just moving the t->utask NULL assignment seemed better. > > Thanks, > Daniel > > diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c > index c75c482d4c52..05f9cedf2691 100644 > --- a/arch/x86/events/core.c > +++ b/arch/x86/events/core.c > @@ -2835,6 +2835,8 @@ static bool is_uprobe_at_func_entry(struct pt_regs *regs) > > if (!current->utask) > return false; > + if (!current->utask->active_uprobe) > + return false; > > auprobe = current->utask->auprobe; > if (!auprobe)
On Thu, Jan 9, 2025 at 6:14 AM Jiri Olsa <jolsa@kernel.org> wrote: > > Max Makarov reported kernel panic [1] in perf user callchain code. > > The reason for that is the race between uprobe_free_utask and bpf > profiler code doing the perf user stack unwind and is triggered > within uprobe_free_utask function: > - after current->utask is freed and > - before current->utask is set to NULL > > general protection fault, probably for non-canonical address 0x9e759c37ee555c76: 0000 [#1] SMP PTI > RIP: 0010:is_uprobe_at_func_entry+0x28/0x80 > ... > ? die_addr+0x36/0x90 > ? exc_general_protection+0x217/0x420 > ? asm_exc_general_protection+0x26/0x30 > ? is_uprobe_at_func_entry+0x28/0x80 > perf_callchain_user+0x20a/0x360 > get_perf_callchain+0x147/0x1d0 > bpf_get_stackid+0x60/0x90 > bpf_prog_9aac297fb833e2f5_do_perf_event+0x434/0x53b > ? __smp_call_single_queue+0xad/0x120 > bpf_overflow_handler+0x75/0x110 > ... > asm_sysvec_apic_timer_interrupt+0x1a/0x20 > RIP: 0010:__kmem_cache_free+0x1cb/0x350 > ... > ? uprobe_free_utask+0x62/0x80 > ? acct_collect+0x4c/0x220 > uprobe_free_utask+0x62/0x80 > mm_release+0x12/0xb0 > do_exit+0x26b/0xaa0 > __x64_sys_exit+0x1b/0x20 > do_syscall_64+0x5a/0x80 > > It can be easily reproduced by running following commands in > separate terminals: > > # while :; do bpftrace -e 'uprobe:/bin/ls:_start { printf("hit\n"); }' -c ls; done > # bpftrace -e 'profile:hz:100000 { @[ustack()] = count(); }' > > Fixing this by making sure current->utask pointer is set to NULL > before we start to release the utask object. > > [1] https://github.com/grafana/pyroscope/issues/3673 > Reported-by: Max Makarov <maxpain@linux.com> > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > --- > kernel/events/uprobes.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > ah, it's interrupt/NMI checking current->utask, makes total sense, thanks for the fix! Acked-by: Andrii Nakryiko <andrii@kernel.org> > diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c > index fa04b14a7d72..5d71ef85420c 100644 > --- a/kernel/events/uprobes.c > +++ b/kernel/events/uprobes.c > @@ -1915,6 +1915,7 @@ void uprobe_free_utask(struct task_struct *t) > if (!utask) > return; > > + t->utask = NULL; > WARN_ON_ONCE(utask->active_uprobe || utask->xol_vaddr); > > timer_delete_sync(&utask->ri_timer); > @@ -1924,7 +1925,6 @@ void uprobe_free_utask(struct task_struct *t) > ri = free_ret_instance(ri, true /* cleanup_hprobe */); > > kfree(utask); > - t->utask = NULL; > } > > #define RI_TIMER_PERIOD (HZ / 10) /* 100 ms */ > -- > 2.47.0 >
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index fa04b14a7d72..5d71ef85420c 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1915,6 +1915,7 @@ void uprobe_free_utask(struct task_struct *t) if (!utask) return; + t->utask = NULL; WARN_ON_ONCE(utask->active_uprobe || utask->xol_vaddr); timer_delete_sync(&utask->ri_timer); @@ -1924,7 +1925,6 @@ void uprobe_free_utask(struct task_struct *t) ri = free_ret_instance(ri, true /* cleanup_hprobe */); kfree(utask); - t->utask = NULL; } #define RI_TIMER_PERIOD (HZ / 10) /* 100 ms */
Max Makarov reported kernel panic [1] in perf user callchain code. The reason for that is the race between uprobe_free_utask and bpf profiler code doing the perf user stack unwind and is triggered within uprobe_free_utask function: - after current->utask is freed and - before current->utask is set to NULL general protection fault, probably for non-canonical address 0x9e759c37ee555c76: 0000 [#1] SMP PTI RIP: 0010:is_uprobe_at_func_entry+0x28/0x80 ... ? die_addr+0x36/0x90 ? exc_general_protection+0x217/0x420 ? asm_exc_general_protection+0x26/0x30 ? is_uprobe_at_func_entry+0x28/0x80 perf_callchain_user+0x20a/0x360 get_perf_callchain+0x147/0x1d0 bpf_get_stackid+0x60/0x90 bpf_prog_9aac297fb833e2f5_do_perf_event+0x434/0x53b ? __smp_call_single_queue+0xad/0x120 bpf_overflow_handler+0x75/0x110 ... asm_sysvec_apic_timer_interrupt+0x1a/0x20 RIP: 0010:__kmem_cache_free+0x1cb/0x350 ... ? uprobe_free_utask+0x62/0x80 ? acct_collect+0x4c/0x220 uprobe_free_utask+0x62/0x80 mm_release+0x12/0xb0 do_exit+0x26b/0xaa0 __x64_sys_exit+0x1b/0x20 do_syscall_64+0x5a/0x80 It can be easily reproduced by running following commands in separate terminals: # while :; do bpftrace -e 'uprobe:/bin/ls:_start { printf("hit\n"); }' -c ls; done # bpftrace -e 'profile:hz:100000 { @[ustack()] = count(); }' Fixing this by making sure current->utask pointer is set to NULL before we start to release the utask object. [1] https://github.com/grafana/pyroscope/issues/3673 Reported-by: Max Makarov <maxpain@linux.com> Signed-off-by: Jiri Olsa <jolsa@kernel.org> --- kernel/events/uprobes.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)